A physical security system is a system that implements measures, such as a barrier, to prevent unauthorized persons from gaining physical access to an asset, such as a building, a facility, or confidential information. Other examples of physical security systems include surveillance systems, such as a system in which cameras are used to monitor the asset and those in proximity to it; access control systems, such as a system that uses RFID cards to control access to a building; intrusion detection systems, such as a home burglary alarm system; Request-to-Exit (REX) systems, such as a system that controls a person's ability to exit a location; and combinations of the foregoing systems.
REX systems typically include one or more of a push-button, a card reader, or a motion detector. For example, when the button is pushed, the motion detector detects motion at the door, or the card reader reads an access card with appropriate credentials, a door alarm is temporarily ignored while the door is opened. In cases in which a lock must be electrically unlocked for exit, the REX system also unlocks the door to allow passage through the exit. Exiting a door without having to electrically unlock the door is called mechanical free passage, which is also a safety feature.
Physical security systems, such as barriers, separate the protected asset, such as a room or building, from other locations, referred to herein as “unsecured”. Unsecured locations may include publicly accessible areas, or areas which are less secure than the “secured location”, which may occur, for example, in the case of a building with multiple levels of security.
A challenge with controlling movement through a passage in a barrier, for example allowing persons to exit through a door from a secured location to an unsecured location, is that persons positioned near the passage may be able to take advantage of the passage opening to enter the secured location without credentials. For example, a person waiting outside a door may slip in through the door as a credentialed person exits. Thus when a person leaves a secured location to enter an unsecured location, the open passage between the two locations creates a security risk since an unauthorized person might be in the unsecured location waiting, for example, for a door to become unlocked and/or opened, and then the unauthorized person may enter the secured location.